Thermostatic control



March 22, 31932, Hf HERTZEERG THERMOSTATIC CONTROL `Original Filed Sept.14. 1927 Patented Mar.. 22, 1932 STATES HARRY HERTZBERG, or BROOKLYN,Nnw YORK, Ass'IGNoR 'ro FRANK a'. KENT, or

/ NEW YORK, N. Y., .AND nnnsnrr, JOINTLY THEBMOSTATIC CONTROLApplication led September 14, 192,7, Serial No. 219,405. Renewed June10, 1931.

rlhis invention relates to a thermostatic control for electrical heatingelements and provides a circuit breaker for preventing eX- cessivetemperature in the heating elements. The invention is particularlyuseful in connection with electrical flat-irons, since the use of suchirons creates peculiar problems that are most eciently solved by theapparatus disclosed herein.

An objectv of the invention is to provide a thermostat that will breakthe circuit positively and quickly after the temperature of theapparatus has passed above the critical point.

The invention also includes the provision of a heating relay for thethermostat, the relay being so arranged that a slight initial movementof the thermostatic element brings into operation the heating relaywhich applies heat directly tothe thermostatic element and hastens theoperation of breaking the circuit to the heating element of the iron, orother apparatus.

Other features of theinvention cooperate to produce a-compact and simpledevice that is positive in operation and having a long useful life..

y While a preferred form of the invention has been disclosed forpurposes of illustra- 30 tion, itl should be understood that various thethermostat has broken the circuit to the heating element.

`Fig. 5 is a section taken at right angles to Fig. 2.

F ig. 6 is a perspective of the thermostat.

Fig. 7 is an enlarged detail of one end of the thermostat.

Referring to the drawings more particularly, the reference numeral 1designates the casing of the connector plug, which is formed ofinsulating material in a well-known manner. An aperture 2 providesentrance for the-feed wires 3, 3, which are attached to binding posts 4and 5. The opposite end of the plug carries spring sockets 6, 6, forcooperation with the posts 7, 7 of the iron. One of the sockets isconnected by a conductor 8 with binding post 4, and the conductor 8carries a lip 9 projecting inwardly and downwardly from the bindingpost 1. The other socket 6 is connected by a conductor 10 with the post11 on which is pivoted the knife switch 12. The outer end of the knifeswitch extends through a slot 13 in the casing and carries an insulatingbutton 14. The inner end of knife switch 12 cooperates with a clip 15mounted on-the binding post 5. A spring 16 engages a finger 17 formed onknife switch 12 and a finger 18 formed on the lower end of the conductor10, and normally biases the switch arm 12 away from the clip 15. lliheswitch arm 12 is held in contact with the clip 15 by a thermostat 19,which will now be described.

IThe thermostat, shown in detail in Figs. 6 and 7, comprises a strip 20of any suitable structure, being preferably formed of two metals havingdierent Vco-etli'cients of thermal expansion, according to well-knownconstruction. rThis Strip 20 is formed so that when cold it assumes aV-shape as shown in Fig. 6. A heating element, which is attached to theinner side of an arm of the thermostat, includes a `Wire-woundresistance core 21 and insulating strips 22 of mica or other suitvablematerial. VMetallic rivets 23, and 23a secure the insulating strips' tothe resistance core and each rivet is in contact with one end of thewire of the core. The heating element is secured to the strip 2O by aclip 24 and a band of insulation 25.y The strip 20 terminates at theouter end of insulation 25, as-

will be clear from Fig. 7, so that the circuit through the resistancecore 21 passes from rivet 23 to winding 21, to rivet 23a, and thence toarm 20.

The thermostat is mounted in the connec-V tor plug by having the eyelet2.6, formed at the juncture of its arms, pivotally engaged over a screwpost 27 placed between the spring sockets 6, 6, the parts being soarranged that in the normal/operating position (Fig.` 2) the left arm ofthe thermostat presses clip 24 against the conductor 8, while the rightarm enga es a notch 28 in the lower side of the knife s 'tch 12 to holdthe switch in contact with clip'15. In this position of the partscurrent iows to the posts 7, 7 of the iron, but no current flows throughthe heating'element of the thermostat, due to the fact that the left armof the thermostat is separated from the conductor 8 by the-insu- .lation25.

If at any time during the use of the flat iron its temperature goesabove a certain pre-determined danger point, the arms of the thermostatimmediately begin to converge, causing the left arm to move from theposition of Fig. 2 to the position of Fig.. 3, causing the-rivet 23 tomake contact with the lip 9. As soon as this occurs current flowsthrough the resistance wire of the heating element 21, which applies astrong local heating eiect along the entire length of the` left arm ofthe thermostat, and quickly causes furtherV contraction-of thethermostat until the right arm becomes disengaged from the notch 28 andfinally reaches the full line position of Fig. 4. This action, ofcourse, breaks the circuit between binding post 5 and conductor 10, aswell as that through the heating element 21. f

4Due to the fact that the arms of the thermostat are contracted againstopposite sides of lip 9, the right arm is out Vof the path of the knifeswitch 12, and it is impossible to immediately reset the switch,to sendcurrent through the heating element of the iron. Before resetting itisnecessary to permit the iron to cooluntil the thermostat relaxes totheldotted position of Fig. 4, at which time the switch can again beplaced in the normal operative position of Fig.` 2.

The structure set forth above has a number of important advantages. Theprovision of a V-shaped pivoted thermostat ermits the use of arelatively longr length of t lermostatic material lwhile stillpreserving the proportions of the conventional connector plug. Thisarrangement of the thermostat also permits the location of its operativeends at points remote from the sockets 6, 6, which is a factor makingfor a compact arrangement.

The provision of the heating relay 21 causes the thermostat to break thecircuit after the temperature of the iron has risen only a shortdistance above the danger point. This is because only a small rise intemperature is needed to move the left arm of the thermostat from theposition of Fig. 2 to that of Fig. 3.

From thisA point the heating relay rapidly boosts the temperature of thethermostat and causes prompt severance of the main circuit through theplug. 4

In addition to these advantages the device has certain features ofrugged and simple construction andrease of assembly that will be evidentto those skilled in the art.

I claim:

1. In combination, a switch for controlling passage of currentthrough acircuit, a thermostat for causing the switch to break the circuit, and aheating element associated with the thermostat for accelerating theaction of the thermostat, said heating element being brought' intooperation by the thermostat.

2. In combination, a switch for controlling passage of current through acircuit, and a V-shaped thermostat pivotally mounted with one of itsarms in a position permitting it to hold the switch closed.

3. In combination, a switch for controlling passage of current through acircuit, a V- shaped thermostat pivotally mounted with one of its armsin a position permitting it to hold the switch closed, and a heatingelement associated with the ,thermostat for accelerating action of thethermostat. p

- 4. In combination, a switch for controlling `passage of currentthrough a circuit, a V- shaped thermostat pivotally mounted with one ofits arms in a position permitting it to hold the switch closed, and aheating element associated with the thermostat for accelerating actionof the thermostat, said heating element being brought into operation bythe thermostat. 5. In combination, a switch Jfor controllin .passage ofcurrent through a circuit, a spring biasing the switch to open position,a V- shaped thermostat pivotally mounted with one of its arms in aposition permitting it to hold the, .switch closed, and a heating ele-`ment associated with the thermostat for accelerating action of thethermostat.

c 7. In combination, a switch for controlling passage of current througha circuit, a spring i biasing the switch 'to open. position, a V- shapedthermostat pivotally mounted with retirees one of its arms in a positionpermitting it to hold the switch closed, and a heating elementassociated with the thermostat for accelerating action of thethermostat, said heating element being brought into operation by thethermostat. Y.

8. A connector plug comprising a pair of sockets, a pair of conductors,each conductor being connected to a socket, a switch connected to one ofthe conductors, a spring biasing the switch to open position, a contactlip connected to the other conductor, a V- shaped thermostat pivotallymounted with one ot its arms in a position permitting it to hold theswitch closed, a heating element associated with the thermostat foraccelerating action of the thermostat., and a contact conductivelyconnected with the heating element, said contact being adapted to bemoved against the contact lip by initial movement of the thermostat.

d 9. A connector plug comprising a pair of sockets, a pair ofconductors, each conductor being connected to a socket, a switchconnected to one of the conductors, a spring thermostat, said meansbeing brought into operation by the thermostat.

13. In combination a switch for controlling passage of current to acircuit, a thermostat for operating the switch, and means associatedwith the thermostat for accelerating the action of the thermostat, saidmeans being brought into operation by the thermostat.

ln testimony whereof I affix my signature.

HARRY HERTZBERG.

biasing the switch to open position, a V- shaped thermostat pivotallymounted with one of its arms in a position permitting it to hold theswitch closed, a contact lip connected to the second conductor andextending between the arms of the thermostat, a heating elementextending along and insulated from the second arm of the thermostat, acontact conductively connected with the heating element, said contactbeing adapted to be moved against the contact lip by initial movement ofthe thermostat.

10. ln combination, a switch adapted to control passage of currentthrough an electrical circuit, a thermostat for causing the switch tobreak the circuit, means comprising a heating coil for heating saidthermostat to accelerate the action of the said thermostat, said coilbeing normally out of the circuit, and thermostatic means for causingcurrent from the circuit to How through the said coil when saidthermostat reaches a predetermined temperature.

1l. A switch comprising a pair of contactsadapted to be placed in anelectrical circuit, one of contacts being movable relative to the othercontact, a thermostatic member adapted to be heated by the currentflowing in the circuit and thereupon permit the contacts to separate,and means comprising a thermostatic member for moving said lirst-namedthermostatic member to close a heating circuit for the said first-namedthermostatic member when the switch parts reach a predeterminedtemperature.

12. In combination, a switch for controlling passage of current througha circuit, a

thermostat for causing the switch to break the circuit, and meansassociated with the thermostat for accelerating the action of the izo

